Exhaust gas recirculation control valve

ABSTRACT

An induction passage vacuum operated valve responsive to exhaust back pressure controls recirculation of exhaust gases from the intake manifold exhaust crossover passage to the intake manifold induction passages. The valve assembly is designed whereby both the induction passage vacuum signal and the exhaust back pressure signal are routed internally of the structural members, thus obviating the need for external hose connections.

Unite States Patent 1 1 Kuehl 1 1 Sept. 4, 1973 [54] EXHAUST GASRECIRCULATION 3,507,260 4/1970 Walker 1. l23/ll9 A 3,641,989 2/1972 Hill123/199 A CONTROL VALVE 3,662,722 5/1972 Sarto 123/119 A [75] Inventor:Paul B. Kuehl, South Bend, 1nd. [73] Assignee: General MotorsCorporation, Primary q w d m Detroit, Mich. A ttorney-J. L. Carpenterand C. K. Veenstra [22] Filed: Apr. 10, 1972 ABSTRACT [21] Appl' 2421420An induction passage vacuum operated valve responsive to exhaust backpressure controls recirculation of [52] US. Cl 123/119 A exhaust gasesfrom the intake manifold exhaust 51 Int. Cl. F02m 25/06 Over Passage tothe intake manifold induction passages- 58 Field of Search 123/119 A;60/278 The valve assembly is designed whereby both the duction passagevacuum signal and the exhaust back 5 R f r Cited pressure signal arerouted internally of the structural UNITED STATES PATENTS members, thusobviating the need for external hose t 1,051,690 1/1913 Colwell. 123/119A connec Ions 2,851,021 9/1958 Covone 123/119 A X 3 Claims, 3 DrawingFigures EXHAUST GAS RECIRCULATION CONTROL VALVE SUMMARY OF THE INVENTIONThis invention relates to exhaust gas recirculation in an internalcombustion engine and more particularly to a novel valve assembly forcontrolling exhaust gas re circulation.

Recirculation of exhaust gases has been developed as a method forreducing formation of oxides of nitrogen during the combustion processin an internal combustion engine. In general, it is desired torecirculate the exhaust gases at a rate proportional to the rate atwhich combustion air flows into the engine, and valves responsive toinduction passage vacuum or throttle position have been utilized forthis purpose.

It also has been recognized that if exhaust gases were recirculatedthrough an orifice into a region of substantially atomspheric pressurein the engine air induction system, variations in exhaust back pressurewould cause the exhaust gas recirculation rateto be proportional to thecombustion air flow rate. However, such a system would require that theexhaust gases pass through at least a portion of the carburetor.

This invention provides a novel valve assembly utilizing the exhaustback pressure to recirculate exhaust gases at a rate proportional to airflow and in a manner which avoids recirculation of exhaust gases throughthe carburetor. In employing this invention, an exhaust gasrecirculation passage is provided which extends from the engine exhaustpassage to the engine air induction passage at a point downstream of theengine throttle. An orifice is provided in the recirculation passage,and a valve disposed downstream of the orifice is operated to create azone of substantially constant pressure in the passage irrespective ofthe wide variations in exhaust back pressure and induction passagevacuum. The rate of recirculation of exhaust gases through the zone thusis proportional to the rate of induction air flow.

In other valve assemblies recently proposed for controlling exhaust gasrecirculation in accordance with exhaust back pressure, the diaphragm orother member responsive to back pressure has directly operated the valvemember which controls the flow of exhaust gases. In the design of such avalve assembly, certain limitations are encountered because the backpressure generally is very low. In the valve assembly of this invention,on the other hand, the exhaust gas flow controlling valve member is notdirectly operated by the member responsive to exhaust back pressure;instead, the valve member is positioned by a member operated by aninduction passage vacuum signal, and the member responsive to exhaustback pressure controls that signal. And as a particular advantage ofthis valve assembly, both the induction passage vacuum signal and theexhaust back pressure signal are routed entirely internally of thestructural members, thus obviating the need for external hoseconnections.

The details as well as other objects and advantages of this inventionare set forth in the remainder of the specification and are shown in thedrawing.

SUMMARY OF THE DRAWING FIG. 1 is a top plan view of an internalcombustion engine inlet manifold having induction and exhaust gascrossover passages, an insert plate having an exhaust gas recirculationpassage mounted on the manifold, and the exhaust gas recirculationcontrol valve assembly mounted thereon;

FIG. 2 is a sectional view along line 22 of FIG. 1 showing theinduction, exhaust gas crossover, and exhaust gas recirculation passagesand also showing the throttle body portion of a carburetor mounted onthe insert plate; and

FIG. 3 is an enlarged sectional view, in elevation, of the control valveassembly, taken generally along line 3--3 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIGS. 1 and2, the combustion air induction passages for the engine are formed inpart by an intake manifold 10 which has a pair of vertical primary riserbores 12 and 14 and a pair of vertical secondary riser bores 16 and 18.Riser bores 12 and 16 open to an upper horizontal plenum 20 connectedforwardly (leftwardly as viewed in FIG. 1) to a pair of transverserunners 22 and 24 and connected rearwardly (rightwardly as viewed inFIG. 1) to another pair of transverse runners 26 and 28. Similarly,riser bores 14 and 18 open to a lower horizontal plenum 30 connectedforwardly to a pair of transverse runners 32 and 34 and rearwardly toanother pair of transverse runners 36 and 38.

Intake manifold 10 also has an exhaust crossover passage 40 whichextends transversely from the left-hand side of manifold 10 beneathplenums 20 and 30 and receives a portion of the exhaust gases dischargedfrom the engine combustion chambers.

An insert plate 42 is secured on manifold 10 and has primary riser bores44 and 46 and secondary riser bores 48 and 50 which meet, respectively,riser bores l2, l4, l6, 18 of manifold 10.

A carburetor 52 is secured on insert plate 42 and has primary throttlebores 54 and 56 which meet, respectively, primary riser bores 44 and 46of insert plate 42. Carburetor 52 also has secondary throttle bores (notshown) which meet secondary riser bores 48 and 50 of insert plate 42.Throttles 57 are disposed in the carburetor bores to control inductionair flow therethrough.

A bore 58 in manifold 10 leads upwardly from exhaust crossover passage40 to the first portion 60 of an exhaust recirculation passage formed ininsert plate 42. The first portion 60 of the exhaust recirculationpassage leads through a control valve assembly 62 to a second portion 64of the exhaust recirculation passage. This second portion 64 dividesinto a pair of branches 66 and 68 which lead to the primary riser bores44 and 46 in insert plate 42.

It should be appreciated that both portions 60 and 64 of the exhaustreciculation passage may be integrated in manifold 10 rather than inseparate insert plate 42. As shown in FIG. 3, control valve assembly 62comprises a valve body 70 having an inlet 72 for receiving exhaust gasesfrom first portion 60 of the exhaust recirculation passage and an outlet74 for discharging exhaust gases to second portion 64 of the exhaustrecirculation passage. An orifice member 76 is disposed across inlet 72,and a downwardly facing valve seat 78 is disposed between inlet 72 andoutlet. 74. A valve member 80, associated with valve seat 78, is formedon a hollow stem 82 carried by a pressure responsive diaphragm 84 andupwardly biased by a spring 86.

A passage 88 senses the pressure in the zone 90 between orifice member76 and valve seat 78 and transmits the zone pressure to the chamber 92above a diaphragm 94. Diaphragm 94 operates against the bias of a spring96 in response to variations in pressure in zone 90 to position a pilotvalve 98 disposed in hollow stem 82.

Hollow stem 82 has lateral openings 100 disposed in the chamber 102between valve seat 78 and outlet 74 and transmits the induction passagevacuum present therein past a valve seat shoulder 101 and valve 98through upper lateral openings 104 to the chamber 106 below diaphragm84. In operation, as the pressure in zone 90 increases, diaphragm 94 isdepressed to move valve 98 away from shoulder 101 and admit manifoldvacuum through openings 104 to chamber 106, thereby decreasing thepressure signal in chamber 106. Diaphragm 84 is then pulled downwardlyagainst the bias of spring 86 to displace valve member 80 from valveseat 78. This operation permits increased recirculation of exhaustgases. Upon a reduction in pressure in zone 90, spring 96 raisesdiaphragm 94 thus closing valve 98 against shoulder 101 and permittingthe pressure signal in chamber 106 to increase as air is bled through aslot 108 in valve member 98 from the chamber 110 between diaphragms 94and 84. Diaphragm 84 is then pushed upwardly by spring 86 to displacevalve member 80 toward valve seat 78, thereby reducing recirculation ofexhaust gases. In practice, diaphragms 94 and 84 will move in unison anda substantially constant pressure will be maintained in zone 90.

The back pressure created in the exhaust passages such as 40 of aninternal combustion engine is generally proportional to the square ofthe rate of combustion air flow through the engine induction passages.The rate of flow of exhaust gases from first portion 60 of the exhaustrecirculation passage through an orifice such as 76 into a zone such as90 of substantially constant pressure is generally proportional to thesquare root of the exhaust back pressure. Thus the rate at which exhaustgases are recirculated is generally proportional to the rate at whichcombustion air flows to the engine.

I Claim:

1. An exhaust gas recirculation control valve assembly for use on aninternal combustion engine having an induction passage for air flow tothe engine, a throttle disposed in said induction passage forcontrolling air flow therethrough, an exhaust passage for exhaust gasflow from the engine, and an exhaust gas recirculation passage having afirst portion extending from said exhaust passage and a second portionextending to said induction passage downstream of said throttle, saidcontrol valve assembly comprising a valve body having an inlet forreceiving exhaust gases from said first portion of said recirculationpassage, an outlet for discharging exhaust gases to said second portionof recirculation passage, valve seat means formed between said inlet andsaid outlet, and an orifice formed in said inlet, valve means associatedwith said valve seat means for controlling flow of exhaust gasestherethrough, and control means for positioning said valve means tomaintain a substantially constant pressure in the zone between saidorifice and said valve seat means, said control means including springmeans biasing said valve means toward engagement with said valve seatmeans, a pressure responsive member connected to said valve means,passage means subjecting said member to a control pressure created byinduction passage vacuum received through a vacuum orifice connectingsaid passage means to said induction passage downstream of said throttleand increased by atmospheric air received through an air bleed orificeopening into said passage means, a bleed valve associated with saidvacuum orifice for controlling admission of vacuum to said passagemeans, pressure responsive means connected to said bleed valve andsubjected to the pressure in said zone whereby upon an increase inpressure in said zone said pressure responsive means displaces saidbleed valve to increase admission of vacuum to said passage meansthrough said vacuum orifice and thereby decreases said control pressureto thereby cause said pressure responsive member to overcome the bias ofsaid spring means and displace said valve means from said valve seatmeans and increase recirculation of exhaust gases, and second springmeans biasing said bleed valve to reduce admission of vacuum to saidpassage means through said vacuum orifice whereby upon a decrease inpressure in said zone said second spring means displaces said bleedvalve member to decrease admission of vacuum to said passage meansthrough said vacuum orifice and thereby increase said control pressureto thereby permit said first spring means to displace said valve membertoward said valve seat means and decrease recirculation of exhaustgases.

2. The control valve assembly of claim 1 wherein said pressureresponsive member is connected to said valve means by a hollow stemwhich provides said vacuum orifice.

3. The control valve assembly of claim 2 wherein said valve seat meansis disposed coaxially with said inlet and said valve stem has a lateralopening between said pressure responsive member and said valve meanswhich defines an opening from a region of induction passage vacuum l l li qg ggy UNITED STATES PATENT oTTTQT:

CERTIFICATE OF @OBRECTWN Patent No. 3,756,210 Dated September 4, 1973Inventofl Paul- B. Kuehl It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 2, line 55, "reciculation" should be recircula- Cancel claims l-3and insert the following:

1. An exhaust gas recirculation control valve assembly for use on aninternal combustion engine having an induction passage for air flow tothe engine, a throttle disposed in said induction passage forcontrolling air flow therethrough, an exhaust passage for exhaust gasflow from the engine, and an exhaust gas recirculation passage having afirst portion extending from said exhaust passage and a second portionextending to said induction passage downstream of said throttle, saidcontrol valve assembly comprising a valve body having an inlet regionfor receiving exhaust gases from said first portion of saidrecirculation passage, an outlet region for discharging exhaust gases tosaid second portion of said recirculation passage, valve seat meansformed between and separating said inlet region and said outlet region,and an orifice formed in a said inlet region, valve means associatedwith said valve seat means for controlling flow of exhaust gasestherethrough, and control means for positioning. said valve means tomaintain a substantially constant pressure in the zone between saidorifice and said valve seat means, said control means including springmeans biasing said valve means toward engagement with said valve seatmeans, a pressure responsive member, a hollow valve stem connected tosaid valve means and said pressure responsive member, said valve stemproviding passage means for subjecting said member to a control pressurecreated by induction passage vacuum and atmospheric air, said valve stemhaving a vacuum orifice connecting said passage means to said inductionpassage downstream of said throttle and an atmospheric air bleed orificeopening into said passage means, a bleed valve disposed in said passagemeans and associated W105) UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION 2 Pa e Patent No. 3,756,210 Dated September 4, 1933Inventofls) Paul B. Kuehl It is certified that error appears in theabove-identified patent and. that said Letters Patent are herebycorrected as shown below:

with said vacuum orifice for controlling admission of vacuumtherethrough to. vary said control pressure created by induction passagevacuum received through said vacuum orifice and by atmospheric airreceived through said air bleed orifice, pressure responsive meansconnected to said bleed valve and subjected to the pressure in said zonewhereby upon an increase in pressure in saidzone said pressureresponsive means displaces said bleed valve .to increase admission'ofvacuum through said vacuum orifice and thereby decreases said controlpressure to thereby cause said pressure responsive member to overcomethe bias of said spring means and displace said valve means from saidvalve seat means and increase recirculation of exhaust gases, and secondspring means biasing said bleed valve to reduce admission of vacuumthrough said vacuum orifice whereby upon a decrease in pressure in saidzone said second spring means displaces said bleed valve member todecrease admission of vacuum to said passage means through said vacuumorifice and thereby increase said control pressure to thereby permitsaid first spring means to displace said valve member toward said valveseat means and decrease recirculation of exhaust gases.

0n the cover sheet, after the abstract, "3 Claims" should I read 1 ClaimSigned and sealed this 26th day of February 19714..

(SEAL) Atte st:

EDWARD M.FLETCHER,JR. C. MARSHALL DANN Atte sting Officer CommissionerofvPatents

1. An exhaust gas recirculation control valve assembly for use on aninternal combustion engine having an induction passage for air flow tothe engine, a throttle disposed in said induction passage forcontrolling air flow therethrough, an exhaust passage for exhaust gasflow from the engine, and an exhaust gas recirculation passage having afirst portion extending from said exhaust passage and a second portionextending to said induction passage downstream of said throttle, saidcontrol valve assembly comprising a valve body having an inlet forreceiving exhaust gases from said first portion of said recirculationpassage, an outlet for discharging exhaust gases to said second portionof recirculation passage, valve seat means formed between said inlet andsaid outlet, and an orifice formed in said inlet, valve means associatedwith said valve seat means for controlling flow of exhaust gasestherethrough, and control means for positioning said valve means tomaintain a substantially constant pressure in the zone between saidorifice and said valve seat means, said control means including springmeans biasing said valve means toward engagement with said valve seatmeans, a pressure responsive member connected to said valve means,passage means subjecting said member to a control pressure created byinduction passage vacuum received through a vacuum orifice connectingsaid passage means to said induction passage downstream of said throttleand increased by atmospheric air received through an air bleed orificeopening into said passage means, a bleed valve associated with saidvacuum orifice for controlling admission of vacuum to said passagemeans, pressure responsive means connected to said bleed valve andsubjected to the pressure in said zone whereby upon an increase inpressure in said zone said pressure responsive means displaces saidbleed valve to increase admission of vacuum to said passage meansthrough said vacuum orifice and thereby decreases said control pressureto thereby cause said pressure responsive member to overcome the bias ofsaid spring means and displace said valve means from said valve seatmeans and increase recirculation of exhaust gases, and second springmeans biasing said bleed valve to reduce admission of vacuum to saidpassage means through said vacuum orifice whereby upon a decrease inpreSsure in said zone said second spring means displaces said bleedvalve member to decrease admission of vacuum to said passage meansthrough said vacuum orifice and thereby increase said control pressureto thereby permit said first spring means to displace said valve membertoward said valve seat means and decrease recirculation of exhaustgases.
 2. The control valve assembly of claim 1 wherein said pressureresponsive member is connected to said valve means by a hollow stemwhich provides said vacuum orifice.
 3. The control valve assembly ofclaim 2 wherein said valve seat means is disposed coaxially with saidinlet and said valve stem has a lateral opening between said pressureresponsive member and said valve means which defines an opening from aregion of induction passage vacuum.